U.S. Pat. No. 3,219,391 discloses a revolving wheel disk cover for a vehicle wheel. The disk cover is attachable to and removable from a vehicle wheel in the same manner as a hubcap. As the vehicle moves, the resulting air flowing past the vehicle causes the disk cover to revolve independently of the wheel itself.
U.S. Pat. No. 5,016,944 discloses a display hubcap apparatus including a cylindrical hubcap disk which is rotatably mounted on a wheel axle by means of a bearing. The hubcap disk includes a message display which rotates with the wheel during vehicle movement but is realigned in horizontal position when the vehicle stops. In order to provide for the realignment of the message display, the hubcap disk includes: a first metallic sphere captured within the outer portion of the hubcap disk; an elongate cylindrical slot diametrically aligned with the first metallic sphere opposite the axial center of the hubcap disk; and a second metallic sphere positioned within the elongate cylindrical slot. During wheel rotation, the second sphere is directed to an outer portion of the elongate slot. However, when the vehicle stops, the second sphere is repositioned in the elongate slot such that the hubcap disk rotates until the message display is horizontally aligned.
U.S. Pat. No. 3,158,946 discloses a hubcap which includes a rotatable outer wire assembly. The outer wire assembly is adapted to continue to spin after the vehicle comes to a stop.
U.S. Pat. No. 1,955,735 discloses a safety hubcap assembly which is positionable on a wheel hub having a threaded outer end. The safety hubcap assembly includes: a hub cover which is threaded onto the hub; a bearing assembly which is positioned around the hub cover; and a rotatable convex safety hubcap which is positionable over the bearing assembly such that the hubcap will rotate independently of the wheel.
In addition to the above, U.S. Pat. No. 2,997,344 discloses a hubcap assembly which includes an outer hub and an inner hub, the inner hub being freely rotatable relative to the outer hub; U.S. Pat. No. 3,611,601 discloses a motorized assembly which is attached to a wheel and rotates independently of the wheel; and U.S. Pat. No. 3,005,906 discloses a hubcap having an ornament rotatably attached thereto.